Meteorologists across the nation have pointed to a "polar vortex" as one of the many systems responsible for what is set to be a rare and extreme-weather weekend. As if the northern U.S. hadn't already recieved its share of wintry weather, the vortex will follow even more snowfall across the north of the country this weekend, this time from Winter Storm Ion.

Ion will move from west to east from late Saturday through Monday, dropping progressively wetter precipitation as it goes. While northerners are no stranger to snowfall, freezing rain and cold weather, most have not experienced a weather phenomenon quite like what the polar vortex promises.

Shown below, this "vortex" is a large counterclockwise-rotating airflow that occurs in the middle troposphere to the stratosphere, centered in the polar regions.

Meteorologists across the nation have pointed to a ‘polar vortex’ as one of the many systems responsible for what is set to be a rare and extreme weather weekend. National Science Foundation

According to the National Weather Service, on Sunday this system is set to push cold arctic air down to the U.S., sweeping across the northern parts of the country, where Americans are still recovering from this week’s winter storms, which killed 16. The NWS has issued hazardous weather warnings for areas ranging from the northern Plains region, the Northeast U.S., to Georgia.

The arctic blast is currently moving southeast across Canada, where wind-chill values dropped to a frigid 50 below zero Saturday afternoon. It is expected to hit the U.S. on Sunday.

The northern Plains region and Midwest look to be the hardest hit, reports the Associated Press. For the first time in 17 years, Minnesota has closed schools statewide as temperatures are expected to range from -10 to -30 degrees Fahrenheit, with wind chills colder than -50 degrees Fahrenheit. This measure was most notably taken in 1996, during which a record-breaking wind chill of 60 below zero was recorded in the northern part of the state.

The vortex will drop temperatures as it moves eastward towards the Midwest and Great Lakes region and is expected to bring temperatures in Chicago down to a high of 11 below zero.

The Green Bay Packers will still host the San Francisco 49ers for the NFC Wild Card playoff game, despite temperatures at Lambeau Field expected to drop to just below zero, according to ESPN. The game reminds fans of the 1967 championship game at Lambeau, when temperatures dropped to -13 degrees Fahrenheit, with an unbelievable wind chill of minus 46 degrees Fahrenheit. The Packers won that game, but the 49ers are favored for Sunday’s game.

The National Weather Service also warns of freezing rain stretching from the Deep South northeastward into New England over the next few days. The northeast of the country, still reeling from the effects of Hercules, can expect icy conditions, temperatures in the teens, and wind chill in the first half of the week.

While the northern part of the country is expected to bear the brunt of the cold this weekend, the blast will drop temperatures as far south as Atlanta, which expects temperatures to range from the low teens to the upper 20s.

As much of the country stocks up on food and hunkers down for the cold, meteorologists across the country are keeping their eyes peeled for potential record-breaking temperatures to register this weekend. As Weather Bell meteorologist Ryan Maue put it, “If you’re under 40, you’ve not seen this stuff before,” reports the Associated Press.